Exhausting of internal combustions engines involves the provision of an exhaust system including an exhaust manifold into which the combustion products are directed from the combustion chamber or chambers of the engine and a pipe leading from the manifold to a silencer of muffler. A tail pipe is usually provided from the muffler, and it is also common to include a catalytic converter in the exhaust gas flow path, usually before the silencer.
The exhaust system nearly always produces a back-pressure when the engine is operating. It has been suggested by some that the back-pressure so generated is beneficial for efficient operation of internal combustion engines. More usually, a maximum back pressure is specified, but no minimum. It is believed by the inventor that the efficient removal of exhaust gases from the engine would provide better performance for internal combustion engines because less energy would be directed to pushing the exhaust gases through the exhaust system.
Exhaust systems have been proposed which include a spiral or helical path for part of the passage between the exhaust manifold and the end of the tail pipe. However, in such arrangements, the spiral flow path is a usually constrained one, or alternatively, only a small butterfly-type baffle is provided. As a result, the angular momentum imparted to the exhaust gases has been limited.
The present invention aims to provide a method of and apparatus for exhausting internal combustion engines which alleviates one or more of the inefficiencies or disadvantages of the prior art. Other aims and advantages of the invention may become apparent from the following description.